The invention relates to a device for the integration of an operating light in an ocular examination instrument.
Such devices are, for example, required for the coagulation of the retina or for photo-surgery on the human eye.
Typically, ocular examination instruments must be able to be rotated through a vertical axis which is drawn through the eye being examined during the examination/treatment process. In addition, the examining instrument should be adjustable in a vertical direction and should be able to be moved by means of a cross-table in the x and y direction.
These adjustment possibilities must be followed by the beam path of the integrated operating laser beam. A device for the integration of the operating light which does not interfere with the adjustability of the ocular examination instrument is known, for example, from the German utility model No. 7 225 429. In this utility model it is proposed that a slit lamp be modified in such a way that the beam of an operating or coagulating laser is directed on to the human eye through the slit lamp. For this purpose, the operating light beam is first introduced into the axis of rotation of the slit lamp which is designed as a hollow shaft, the operating light beam is deflected out of the axis of rotation by means of a mirror above the sweep arm of the slit lamp and by means of a second mirror is introduced into the beam path of the slit lamp. The operating light beam then enters the normal beam path system of the slit lamp through a bored mirror and runs parallel to the illuminating light of the slit lamp behind this bored mirror.
This known device has a number of disadvantages:
To integrate the operating light beam, it is necessary to make adjustments to the beam path system of the slit lamp which have a considerable effect on its functioning. Despite these adjustments, the beam path system of the slit lamp limits the aperture of the laser beam to very small values.
Furthermore, as a result of the many optical surfaces the operating light beam passes through in the slit lamp "ghost pictures" and reflections of the operating light beam may occur. This may also have the effect that part of the operating light enters the eye of the patient in an incorrect way and causes unintentional damage there.
In addition, the operating light is also partially guided without any casing in the area between the axis of rotation and the split lamp.
Also, in the known device only the light of an operating laser is integrated in the beam path of an ocular examination instrument. However, when for example, a neodymium YAG laser, which operates in the infra-red range, is used as the operating light source, it would be advantageous if additionally a "target laser" whose light is in the visible spectral range were used as an observation light source or as a target light source.
As the operating light beam is directed via the slit lamp in the known device, the operating light beam and the observation beam path can never be coincident when advantage is taken of the fact that the slit lamp can be rotated independently of the observation instrument. However, as it is necessary in many applications for the operating light beam and the observation beam path to be coincident, the free rotation function of the slit lamp with regard to the observation area can, for this reason, and as has been recognised according to this invnention, not be made use of in the known device.
A device of another kind, in which the light of an operating laser is introduced into the beam path of an ocular examination instrument by a mirror, is known from U.S. Pat. No. 3,769,963. With this device, the light of the operating laser is introduced by a mirror into the beam path between the eye under examination and the observation instrument, while the light of the illumination laser is led to the eye by a light conductor. In addition, the light of the illumination laser can be introduced into the beam path of the operating laser by a mirror in such a way that the light beam of the illumination laser can also be used as a target light beam.
This known device of another kind has, however, the disadvantage that--to ensure that the ocular examination instrument can be vertically adjusted and rotated within the usual limits--the light of the laser has to be led over long stretches by a flexible glass fiber conductor. Such glass fiber conductors are, however, particularly prone to disturbance for light in the infra-red range. Furthermore, this proneness to disturbance is increased if their flexibility is subjected to a lot of strain so that, where possible, the use of such flexible light conductors should not be considered, particularly for lasers which operate in the infra-red range.
The object of this invention is to provide a device for the integration of operating light in a rotatable and adjustable ocular examination instrument, whereby operating light beam and, if required, also an observation and/or target light laser can be integrated in the beam path of the observation instrument without interfering with the adjustability or rotatability and without the use of flexible light conductors or disturbing articulated optical systems and without interfering with the optical system of the ocular examination instrument.
The underlying problems are solved according to the present invention in that a first optical device deflects the coaxial light beams into the pivot arm of the observation apparatus, in that a second and a third optical device are attached in or on the pivot arm, in that the second optical device deflects the light beams parallel to the axis of rotation of the instrument, in that the third optical device integrates the light beams into the beam path of the observation apparatus and in that, if additional observation and/or target beams are to be integrated, the light beams of the observation and/or target source are conducted coaxially to the operating light beam.
According to this invention the operating light beam and, where required, the observation and/or target light beams directed coaxially to the operating light beam, are first directed into the axis of rotation of the ocular examination instrument and then integrated in the beam path of the observation instrument outside this revolution axis. In this way, the vertical adjustability and the rotatability of the ocular examination instrument remain unaffected. By diverting the coaxial light beams into the sweep arm of the observation instrument, there is no need to make any adjustments to the optical structure, for example, of the slit lamp.
In this way, the device according to this invention has the advantage that the coaxial beams are guided completely within parts of the mounting of the ocular examination instrument and that the beam path is completely encapsulated without any additional construction effort.
In this context coaxial beam guidance means a beam guidance in which the axes of the individual laser beams coincide; as a non-essential requirement one of the laser beams should have a ring-shaped cross-section.
According to another feature of this invention, a large aperture can be attained which is required for small spot sizes of the operating light beam in the order of 10 .mu.m.
The expanding optical system of this invention may consist of two optical elements, where one has a negative and the other a positive refractive power. The optical elements can thereby be single lenses or several lenses.
The rotatability of the third optical element according to this invention allows the integration of the beam path of other devices, for example of an photographic device, into the beam path of the ocular examination instrument so that the device according to this invention, can be used universally.
Moreover, ghost pictures, reflections, etc. resulting from the mirror-effects etc. are effectively suppressed in the arrangement according to this invention.
The fixed arrangement of the light sources according to this invention is of particular advantage when, for example, the light sources, and in particular the lasers, are large and heavy and thus cannot be attached to the ocular examination instrument itself.
The device according to this invention can be used in conjunction with the most varied ocular examination instruments, for example in conjunction with a slit lamp instrument or with an ophthalmoscope.